Question: Simplify the following expression: $n = \dfrac{4}{7r + 1} \div \dfrac{5}{2r}$
Explanation: Dividing by an expression is the same as multiplying by its inverse. $n = \dfrac{4}{7r + 1} \times \dfrac{2r}{5}$ When multiplying fractions, we multiply the numerators and the denominators. $n = \dfrac{ 4 \times 2r } { (7r + 1) \times 5}$ $n = \dfrac{8r}{35r + 5}$